Tablets and pills are well known. They are generally the preferred vehicles for oral administration of both prescription and over the counter medications. There are certain situations, however, in which the use of tablets or pills is undesirable. For example, individuals with laryngeal inflammation or esophageal disorders may have difficulty swallowing. In other cases there is no liquid available to aid swallowing. Small children often find it difficult to swallow pills and/or may choke in the attempt. An alternative to tablets and pills is the use of liquid medicaments, e.g., elixirs and syrups. Liquid medicaments have their own drawbacks, however, including imprecise dose measurement and, in the case of oral administration to young children, loss of some or all of the medicament via deliberate or accidental rejection.
An ideal alternative would be a solid dosage form that can be administered orally, which rapidly disperses in the mouth, and hence does not require great effort in swallowing. Such an idealized approach minimizes the possibility of rejection, if administered to a young child, and yet remains stable in composition and structure over a reasonable period of time, i.e., has adequate shelf life. Suitable rapidly dispersing dosage forms could also be used in other applications, including the treatment of wounds and other bodily insults and diseased states in which release of the medicament by externally supplied moisture is not possible.
There have been prior attempts to make stable and quick dispersing dosage forms. Effervescent dosage forms and quick release coatings of insoluble microparticles are described in U.S. Pat. Nos. 5,578,322 and 5,607,697. Freeze dried foams and liquids are described in U.S. Pat. Nos. 4,642,903 and 5,631,023. Melt spinning of dosage forms is described in U.S. Pat. Nos. 4,855,326, 5,380,473 and 5,518,730. Each of these dosage forms has drawbacks that limit their usefulness.
In particular, effervescent dosage forms, while providing rapid dissolution, require that a combination of an acid and an alkali be used. This limits the type of active ingredients (i.e., medicaments) which can be incorporated in the dosage form to those which are insensitive to acid or alkali levels. Moreover, the coating of microparticles may affect the oral release of the microparticles themselves, but not necessarily the oral release of the free form of the medicament contained in the microparticles.
Freeze-drying is a complex process and limits the scope of suitable medicaments to those having good solubility and relatively low density. Freeze dried dosage forms are also fragile and, hence, may require special handling and packaging. On the other hand, melt spinning requires that both medicament and a carrier be forced at high temperature and pressure through a small orifice, which requires the use of highly heat stable medicaments and results in a malleable amorphous product best described as a wool or fiber.
An alternative manufacturing processes is solid, free-form fabrication (SFF), which is a technique capable of creating complex structures via a layering process. One example of SFF is three-dimensional printing (3DP) which employs computer-aided design (CAD) to construct components in a sequential laminating process. U.S. Pat. No. 5,490,962 relates to the use of 3DP for the preparation of various medical devices. This patent is silent, however, and does not address the problems associated with oral administration under the situations described above, nor does it disclose, teach, or suggest the construction of rapidly dispersing dosage forms. It should be noted that this patent, as well as any other reference cited in the present specification, is incorporated by reference herein in its entirety.
Hence, there remains a need in the art for a convenient, pre-measured dosage form that is stable, and yet is suitable for oral administration to small children and others having difficulty in swallowing. There is also a need in the art for a dosage form suitable for placement in a non-oral body cavity, body surface, or exposed area which can effect rapid release of a medicament without the need of applying (i.e., without necessarily being accompanied by) externally supplied moisture. These needs are met by the dosage form of the present invention, as described further below.